{timeline} lays events out on a time axis and writes them as inline SVG (tags/_lib/timeline.php). The rows come from data= as for {chart}, or from the content of the pair - JSON, YAML, XML or CSV.

A row with a date is a moment: a dot on the axis and a card above or below it with the label and, under it, the text. The sides alternate, and a card that would cover another card or a leader line moves to the other side or a lane further out. A row with from and to is a span, drawn as a bar in a lane under the axis with its label inside or beside it; moments and spans mix in one timeline. Left out, date is the first field that reads as a date, and label and text the first other text fields.

The axis gets round ticks by the span it covers - years in steps of 1 to 100, months by 1, 3 or 6, or days - and the dates on the cards are written by their precision, or by format. color groups the events by a field, a colour each with a legend. vertical puts the events one under the other instead, dates left and cards right, which suits a long list or a narrow column.

Every event has a <title> and the <desc> lists them all. A timeline without rows answers nothing, so its @else@ shows; rows of which none has a usable date are an error under the strict check. For a month grid see {calendar}, for a project plan with progress {chart 'gantt'}.